1. Field of the Invention
The present invention pertains to rotary electric shavers having a plurality of circular cutting heads at the distal end of the shaver that are driven by a single electric motor within the shaver body.
2. Description of the Prior Art
Rotary electric shavers rely primarily upon the rotation of circular cutting elements within the shaver heads and hand movements of the entire shaver across the surface of facial skin in order to maximize the volume of hair shaved and how closely the hair is shaved. The prior improvements disclosed for rotary electric shavers with a plurality of cutting heads have concentrated on more effective designs and shapes for the cutting head elements, their flexibility and comformity to the skin surface and the configurations of the gear chains that drive these improvements. Izumi U.S. Pat. No. 5,983,501 discloses multiple planetary gear chain assemblies that are stacked within a cylindrical housing and around multiple drive axes for the purpose of driving both an inner set of high speed cutting heads and a surrounding outer set of low speed cutting heads all of which are supported within a stationary cutting head frame. Izumi U.S. Pat. No. 6,212,776 discloses an improved version of the rotary shaver that rotates the inner and outer cutting elements within each cutting head at different speeds by means of multiple drive shafts and gears that mesh with external gear teeth on the underside of each outer cutting element and wherein all cutting heads are contained and supported within a stationary head frame. Kakimoto U.S. Pat. No. 6,317,983 discloses another version of a rotary electric shaver having inner and outer cutting elements that rotate with respect to each other within cutting heads that are contained and supported within a stationary head frame. None of the past rotary shaver improvements have disclosed a concept and means for combining planetary and rotational movement of a plurality of rotary cutting heads driven by a central drive shaft of a single electric motor.
The present invention arose as a result of an absence in prior art of a simple solution to some of the problems associated with the use of the rotary electric shavers that are now widely marketed. The major problems are that rotary electric shavers require an excessive amount of time and an excessive amount of physical effort to achieve a close shave. The present invention eliminates these problems by substantially increasing the volume of hairs cut and the area of skin shaved by the cutting heads.
The factors determining the time and effort required for shaving with a rotary electric shavers are the circular movements of the cutting elements within the cutting heads and the movement of these cutting heads across the facial skin. In the present invention, a motorized sweeping motion of all the cutting heads across the facial skin is substituted for the user""s slow, erratic hand movements of the entire shaver and the cutting heads. This is accomplished by rotating the cutting head frame within the body of the shaver. The planetary motion of the cutting heads eliminates the slow, circular movement of the shaver by hand as recommended by all manufacturers of rotary electric shavers.
For any interval of shaving time, the motorized planetary motion of all the cutting heads, in addition to the rotary motion within the cutting heads, produces a closely shaved area of skin and a volume of hair cuttings that can be two or three times the amount produced by the rotation of the cutting head elements without the additional superimposed motion of the rotating frame. This represents an improvement far in excess of what can be expected from any of the past improvements that have been made to the rotary cutting heads and their cutting elements.
An additional benefit of the rotating frame is that the planetary motion of the cutting heads enables the user to shave confined facial areas, such as above and below the lips with a single horizontal motion of the shaver instead of the repeated scrubbing with the uppermost cutting heads and hand maneuvering of the shaver body, as required with conventional rotary electric shavers.
The simple drive means for the rotatable frame and the use of existing drive gears as part of a speed reduction chain, as well as the use of the same electric motor as currently used, permits the rotatable frame to be incorporated within the structure of a triple-headed rotary electric shaver without great difficulty or prohibitive tooling costs. Furthermore, shaver improvements such as flexible or floating cutter heads and sideburn hair trimmers can easily be added to the rotary electric shaver described by the present invention.